ABSTRACT Dr. Peyton Thompson is an Assistant Professor of Pediatric Infectious Diseases at the University of North Carolina (UNC) who is applying for a K08 Mentored Clinical Scientist Career Development Award. Dr. Thompson?s long-term career goal is to become an independent physician-scientist with expertise in vaccinology and the epidemiology of vaccine-preventable diseases in low-resource settings. The prevalence of hepatitis B virus (HBV) is unacceptably high in sub-Saharan Africa given that there is an effective vaccine against HBV. In order to design improved vaccination strategies to protect vulnerable individuals against HBV, we must first address two important HBV-related knowledge gaps: 1) Geospatial drivers of HBV infection in African children, and 2) HBV household transmission patterns in African children. This proposal will address these knowledge gaps using epidemiological data and dried-blood spot samples from a large national survey in the Democratic Republic of the Congo (DRC). This application will address the following specific aims: Aim 1) Locate hotspots of high HBV prevalence and low population-level immunity among Congolese children using existing DBS samples from a nationally representative survey; Aim 2) Identify patterns of HBV transmission at the household level using phylogenetic approaches; and Aim 3) Estimate the impact of targeted vaccination strategies in the DRC using modeling techniques. These aims align with Dr. Thompson?s career development goals: 1) Training in epidemiological and spatial analyses of large data repositories; 2) Training in vaccinology; and 3) Training in impact modeling. To achieve these goals, Dr. Thompson has assembled a highly qualified mentorship team comprised of: her primary mentor, Dr. Sylvia Becker-Dreps, a global health researcher with expertise in vaccine-preventable diseases; her co-mentor, Dr. Steven Meshnick, a skilled epidemiologist with vast experience in the DRC; an internal advisory committee consisting of experts in analysis of large data (Dr. Jonathan Parr), hepatology (Dr. Michael Fried), spatial analyses (Dr. Michael Emch) and vaccinology (Dr. David Weber). This multidisciplinary team of NIH-funded researchers has an impressive track record of training junior investigators toward independent research careers. Under their supervision, Dr. Thompson will achieve the research and career development aims in this proposal, and will be prepared to apply for an R01 to implement and evaluate spatially targeted vaccination strategies specific to the DRC.